She is one of our most acclaimed actresses, a national treasure and double Oscar nominee, popular with public and critics alike.

But former Birmingham nurse Julie Walters has revealed, inside she still feels a frightened little girl who feels she isn’t good enough, burdened by childhood memories of her pushy mum’s disapproval.

So the the 65 year-old star of Educating Rita, Calendar Girls and the Harry Potter films, believes her career has been fuelled by a lifelong desire to gain the praise she was denied as a little girl.

“There’s definitely that need for love and approval and appreciation,” says Julie, who was brought up in Smethwick. “And I don’t know whether I literally hear her saying stuff, but there are moments when I think ‘I’m not good enough’.

“It’s a feeling in my heart. It’s always there and the three year old or ten year old in you can come to the surface at any time. I was a frightened little person in many ways.”

Julie’s mother Mary left County Mayo in Ireland seeking a better life in Britain and, after marrying builder and decorator Thomas Walters, developed ambitious plans for her family.

Julie’s two brothers both went into teaching and, at the age of 18 after being privately educated, Julie started to train to be a nurse at Queen Elizabeth Hospital, in Edgbaston. But within 18 months she’d quit and furious Mary, who was a clerical assistant for the Post Office, predicted her daughter would be in the gutter by the age of 20.

“I did challenge her about it,” says Julie. “I said: ‘Why were we never good enough?’ And she said: ‘I wanted you to be competitive’ And I said: ‘Well, we just felt inadequate’.

“She just felt that SHE wasn’t good enough – she was an immigrant.”

Julie started studying English and drama at Manchester Polytechnic. But even when she went on to work for the Everyman Theatre in Liverpool – alongside the likes of Bill Nighy, Pete Postlethwaite and Jonathan Pryce – her mother refused to watch any of her early acting performances.

Only after her death in 1989 did she discover Mary had kept a collection of newspaper clippings charting her daughter’s amazing career.

But it wasn’t only her mother who struggled to cope with Julie moving into the alien world of acting. Initially Julie herself struggled to make the transition.

In 1983, when she paired up with Michael Caine to make movie Educating Rita, she empathised with the tale of a working class girl dealing with middle class prejudices.

Julie Walters arriving at The EE British Academy Film Awards 2015

Talking during a one-on-one chat with Richard E Grant to be broadcast on BBC Four on Sunday, Julie says: “I can still remember Michael saying: ‘There’s a lot of anger in you’. And he was right, there was a bit of a chip on my shoulder.

“I still felt that thing of coming from that sort of background and going to college where I was then surrounded by middle class people.”

But Julie soon discovered the more enjoyable side of being an actress. She was nominated for an Oscar for her performance in Educating Rita, and won the first of five BAFTAs, before being offered a film role by Smokey and the Bandit superstar Burt Reynolds.

When she politely declined, he still invited her to his home in Florida. But when she got there she had a bit too much to drink and embarrassed herself.

“Your eyes do want to keep going up to the thatch. I was with his publicist and I said: ‘We mustn’t mention the word ‘wig’!’ Because there’d recently been a TV interview with Burt and Dolly Parton as they’d just done a film together. She said: ‘We have two things in common – we both have 40 inch chests and we both wear wigs’ and Burt hadn’t liked this.

“Anyway, we sat down for inner and it just came out: “WIG!” and I had to turn that into “WE’RE Going to Los Angeles!”

In 1987 she took the lead role in Personal Services, inspired by suburban brothel keeper Cynthia Payne, who gave Julie a unique insight into her world.

“The first time I met her was in a very posh restaurant in London,” says Julie. “It was very quiet and in comes Cynthia and she never even said hello, she just said: ‘Do you like sex Julie?’ And I said: “Well, it depends who it’s with.’

“Then she goes in her bag and out come these photographs, pictures of people in all sorts of eyewatering poses. There was one man lying on the floor covered in something, I don’t know what it was.

“She said: ‘That’s my bank manager, that is’ And I said: ‘What’s that all over him?’ And she says: “It’s hoover dust – that’s what he likes Julie.’”

In 2000 the mum of one landed a role playing the dance teacher in hit movie Billy Elliott. Although it earned her a second Oscar nomination, as best supporting actress, it wasn’t easy for Julie who, at the age of 50, was going through the menopause.

“I was hot flushing constantly,” she says. “Can you imagine having the menopause and having to learn all that dance? The steps were so fast and the choreographer didn’t smile once. I only did one sequence all the way through.”

She had a different challenge to overcome in 2003’s Calendar Girls, the story of a WI group in North Yorkshire who posed naked to raise money for charity. Thankfully on the big day the cast were to disrobe, her esteemed co-star Helen Mirren provided some Dutch courage.

Julie says: “Everybody was scared stiff. So Helen brought champagne in and we all got plastered the night before which only made it worse the next day – we were feeling absolutely dreadful.”

In 2008 she enjoyed another career peak: she was awarded the CBE and starred in the movie version of Abba musical Mamma Mia! alongside Meryl Streep.

“It was so intimidating because I’d grown up with her and revered her on the screen,” says Julie. “Then suddenly you’re working next to her, talking about colds and the menopause.”

In 2011 she appeared, for the last time, as Molly Weasley, mother of Ron Weasley, in Harry Potter and the Deathly Hallows, Part 2. It was a role she’d played in the film franchise for ten years.

“It was so sad when I finished,” she says. “It wasn’t a very big part, but it was going in every year to the same group of people. I just loved it and it’s rare you have that kind of structure in your life as an actor.”

Last year Julie, who lives with her husband on an organic farm near Plaistow in West Sussex, was awarded the BAFTA Fellowship acknowledging a career which seems unstoppable.

“I did imagine stopping when I reached 60,” she says. “My hair was white and there was something about that and turning 60, I thought ‘I could actually retire’. But I didn’t know what I wanted so I didn’t do anything for a year. Then suddenly a script came from the National Theatre and I thought: ‘Oh this is marvellous...well, obviously I haven’t finished.”

Julie has been back on our small screens this year in Channel 4’s Indian Summers playing Cynthia Coffin, a British hostess living in India in the age of the British Raj.

“I’m going to do the second series of Indian Summers, that’s the next thing,” she says. “Now I know there are so many things I don’t want to do and I feel it’s alright not to do them.

“But Indian Summers made me say: ‘Oh I’d like to do that.’”

• Julie Walters was interviewed at a special British Film Institute screening, being broadcast on BBC Four on Sunday at 8pm.